Shark Week Preview: Why Scientists Set Themselves Adrift for 7 Days in ‘The Lost Cage’

Discovery’s Shark Week continues Wednesday with two specials that take viewers to places that may feel entirely new.

In The Lost Cage (9 p.m.), a team of biologists sets out to determine if man-made fish aggregating devices (FADs) used by commercial fishermen to create artificial reefs that attract tuna also lure in sharks, which may then get caught in their nets. To do that, they turn an aluminum cage into an ecosystem and set themselves adrift for seven days in the Gulf of Mexico aboard a research raft (nicknamed the Man o’ War) floating above it.

The goal is to tag sharks and see if they follow the cage, which, much like the oil rig in the clip above, becomes a pit stop in the open ocean. If a tagged shark returns and comes within 300 feet of the Man o’ War, a signal will be heard. (Spoiler alert: It happens. Seven days and more than 200 miles later, the real star of the show, an aggressive 9-foot mako they name Scar, reappears, suggesting sharks have learned that FADs are a good place to hunt and may be in danger.)

The clip below gives you a taste of some of the hour’s most tense moments — night dives.

Devil Sharks (10 p.m.), meanwhile, explores the reasons why volcanoes — whether active, dormant, or extinct — are shark hot spots around the globe. Florida International University’s Mike Heithaus and his team conclude that the mild magnetic field in undersea lava ridges in the Caribbean may become a roadway guiding sharks from island to island. As the sneak peek below shows, mazes of lava tubes off Hawaii are used for shelter by smaller sharks, like whitetip reefs, to hide from bigger sharks that prey on them.

The hour culminates with a trip to the Rangiroa atoll in French Polynesia. The lagoon’s shallows are a nursery for blacktip reef sharks, but it’s in the deep water outside where you get the hour’s most thrilling sequence — when French freediving champion Francis Le Gall, who can hold his breath up to four minutes, tries to get a tissue sample from a pack of silvertip and grey reef sharks with his spear gun. He’s lining up a shot when, all of the sudden, the sharks disappear. Enter a 12-foot tiger…